Iron is an essential trace element required for growth and development of living organisms. In mammals, iron content is regulated by controlling iron absorption, iron recycling, and release of iron from the cells in which it is stored. Iron is predominantly absorbed in the duodenum and upper jejunum by enterocytes. Iron is recycled from degraded red cells by reticuloendothelial macrophages in bone marrow, hepatic Kupffer cells and spleen. Iron release is controlled by ferroportin, a major iron export protein located on the cell surface of enterocytes, macrophages and hepatocytes, the main cells capable of releasing iron into plasma. Hepcidin binds to ferroportin and decreases its functional activity by causing it to be internalized from the cell surface and degraded. (Nemeth et al., Science, 306:2090-3, 2004).